1. Field of the Invention
The present invention relates to an automatic lay-up machine including a head device and a support mechanism. The head device includes a sheet supplying unit, a lay-up unit, and a sheet take-up unit. A raw-cloth roller having a long prepreg sheet wound therearound is mounted in the sheet supplying unit, and the sheet supplying unit supplies the prepreg sheet from the raw-cloth roller. The prepreg sheet includes sheet-shaped prepreg and release paper bonded to a surface of the prepreg. The lay-up unit lays up the prepreg on a receiving surface by pressing the prepreg sheet supplied by the sheet supplying unit against the receiving surface with a lay-up head. The sheet take-up unit takes up the release paper separated from the prepreg when the prepreg is laid up. The support mechanism supports the head device and includes a mechanism for moving the head device at least in a lay-up direction of the prepreg and a width direction of the prepreg sheet.
2. Description of the Related Art
Composite materials are used in aircraft-related components, automobile-related components, and sports and recreational goods. The composite materials are manufactured by forming a prepreg laminate into a predetermined shape and then pressing and heating the prepreg laminate. The prepreg laminate is obtained by laying up prepreg in which reinforced fiber, such as carbon fiber or glass fiber, is impregnated with an epoxy resin or the like.
The prepreg is generally laid up manually or by an automatic lay-up machine. The automatic lay-up machine lays up the prepreg by pressing a prepreg sheet supplied from a raw-cloth roller against a receiving surface with a lay-up head. Examples of the types of automatic lay-up machines include a type in which the raw-cloth roller is fixed and a type in which the raw-cloth roller moves together with the lay-up head.
A prepreg lay-up machine disclosed in Japanese Unexamined Patent Application Publication No. 6-55656 is an example of an automatic lay-up machine of the type in which the raw-cloth roller moves together with the lay-up head.
This prepreg lay-up machine includes a device (head device) including a let-off unit (sheet supplying unit), a lay-up unit, and a take-up unit (sheet take-up unit). A raw-cloth roller having long prepreg tape (prepreg sheet) wound therearound is mounted in the let-off unit (sheet supplying unit), and the let-off unit (sheet supplying unit) supplies the prepreg sheet from the raw-cloth roller. The prepreg tape (prepreg sheet) includes sheet-shaped prepreg and separation paper (release paper) bonded to a surface of the prepreg. The lay-up unit lays up the prepreg on a receiving surface by pressing the prepreg sheet supplied by the let-off unit against the receiving surface with a lay-up roller (lay-up head). The take-up unit (sheet take-up unit) takes up the release paper separated from the prepreg when the prepreg is laid up. In addition to the head device, the prepreg lay-up machine also includes a support mechanism (not shown) that supports the head device and includes an apparatus body (mechanism) that moves the head device three dimensionally (for example, in the lay-up direction of the prepreg and the width direction of the prepreg sheet). This prepreg lay-up machine lays up the prepreg by placing the prepreg next to the previously deposited prepreg with a predetermined gap therebetween in the width direction thereof, and automatically stops laying up the prepreg when the gap exceeds a predetermined allowable value.
In the automatic lay-up machine of the type in which the raw-cloth roller moves together with the lay-up head, the raw-cloth roller is positioned with respect to the receiving surface in the width direction when a lay-up operation is started. The prepreg is laid up by moving the raw-cloth roller and the lay-up head in a direction in which the receiving surface extends and pressing the prepreg sheet against the receiving surface with the lay-up head. In the lay-up process, even when the raw-cloth roller is moved while the position of the raw-cloth roller coincides with position of the receiving surface in the width direction, the prepreg sheet pressed by the lay-up head may become displaced from the receiving surface in the width direction. Such a displacement may be the result of the following.
That is, the prepreg sheet wound around the raw-cloth roller includes portions in which the internal stress (residual stress) is not uniform in the width direction. This is because although the prepreg sheet is wound around the raw-cloth roller while a tension is applied thereto, the tension distribution in the width direction is not appropriately managed.
When the prepreg sheet is supplied from the raw-cloth roller in the lay-up process, the internal stress in the prepreg sheet is released. As a result, a deviating force is generated in the prepreg sheet (prepreg) in the width direction, and the above-described displacement occurs.
Since the raw-cloth roller and the lay-up head are arranged such that the positions thereof coincide with the position of the receiving surface in the width direction, the deviation of the prepreg sheet (prepreg) appears as a displacement of the prepreg sheet (prepreg) with respect to the lay-up head in the width direction. In other words, when the displacement occurs, the position of the prepreg sheet (prepreg) with respect to the lay-up head in the width direction is shifted in the width direction from that at the start of the lay-up operation.
The amount of deviation of the prepreg sheet (prepreg) due to the internal stress is small, so that the displacement of the prepreg with respect to the receiving surface in the width direction caused in a single lay-up operation does not affect the quality of the prepreg laminate obtained as a result of the lay-up operation. However, if the next and following lay-up operations are performed without correcting the above-described displacement of the prepreg sheet (prepreg) with respect to the lay-up head in the width direction, the displacement gradually increases.
When the prepreg is laid up on the receiving surface while being displaced in the width direction by a large amount, a prepreg laminate that can be formed into a desired shape cannot be obtained. Thus, the quality of the prepreg laminate is degraded.
In addition, in an automatic lay-up machine in which prepregs are arranged next to each other in the width direction as described in Japanese Unexamined Patent Application Publication No. 6-55656, constant gaps cannot be provided between the adjacent prepregs. As a result, a prepreg laminate having a desired strength cannot be obtained, and the quality of the prepreg laminate is degraded.